Checking for valid credit card numbers.... lots of syntax errors.

At this point I'm fairly certain the code will run properly once I clear up all syntax errors. However I'm not really sure how to do this as I am not entirely familiar with Java. Any help is appreciated.

Thanks for your help everyone I'm now using NetBeans. I'm seeing lots of errors but I'm not sure how to fix them. The most common is "class, interface, or enum expected" ?

import javax.swing.*;

public class Main {
      public static void main(String[] args) {
        String cCNum;
        int count= 0;
  do {

     cCNum= JOptionPane.showInputDialog(null,"Please enter a 13 or 16 digit" +
             " credit card number");
     count++;
      if ( cCNum.length() < 13 )
                cCNum= JOptionPane.showMessageDialog(null, "The credit card number is" +
                        " too small please look at the number and re-enter it");
      else if ( cCNum.length() >16 )
                cCNum= JOptionPane.showMessageDialog(null, "The credit card number is" +
                        "too large please look at the number and re-enter it");
     }

  while ( (cCNum.length() < 13) || (cCNum.length() > 16) && (count < 3) && validInt (cCNum) ));

        if (count > 3){

        JOptionPane.showInputDialog(null,"The numbers you entered were not " +
                "valid.\nGoodbye.");   
         System.exit(0);
        }
        else {


         JOptionPane.showMessageDialog(null,"Your credit card number is:"+ cCNum);
         JOptionPane.showMessageDialog(null,"Your card is a" + cCType (cCNum) );
            JOptionPane.showMessageDialog(null,"Your card is" + isValid(long.parselong(cCNum)) );
        }


      public static String cCType (String cC){
          if (cC.startsWith("4")){
              return "Visa";
          }
          else if (cC.startsWith("5")){
              return "MasterCard";
          }
          else if (cC.startsWith("6")){
              return "Discover";
          }
          else if (cC.startsWith("37")){
                return "American Express";
          }
          else 
              return "Unknown card type";
      }

    public static boolean validInt(String num ){

      try {
            long.parselong (num);
            return num.length()== 13 || num.length()== 16;                     
        }catch(NumberFormatException e){
         //If it is not a valid number return false.
            return false;
        }
    }
      public static boolean isValid (long num){
         boolean error = false;

         if  ((sumOfEvenPlaces(num)+ sumOfOddPlaces (num))% 10) == 0)
                 return true;
         else
             return error;
     }



   public static int sumOfEvenPlaces (long num) {
       int total= 0;
       int add= 0;
       number = (num)/10;
       while (num !=0){
            add= getDigits((num %10))*2;
            total+=add ;     
            number = (num)/100;
       }
        return total;       
   }

   public static int getDigits(int num)  {
        if ( num >= 10 ) {
            return (num % 10);       
            }
        else
            return num;
    }       

   public static int sumOfOddPlace(long num)  {
        int total = 0;
        while (num > 0) {
            sum += ( number % 10 );
            num = (num)/100; 
        }
        return total;
    }
 }
}

From stackoverflow

• You should give more details about what is wrong. But as far as I can see...

  a) you're not closing cCType method. You forgot to put "}" before the declaration of the validInt method.

  b) also, you're not closing quotes in the "unknow card type".

  public static String cCType (String cCNum)
                if (cCNum.charAt(0)=="4")
                    return "Visa";
                else if (cCNum.charAt(0)=="5")
                    return "MasterCard";
                else if (cCNum.charAt(0)=="6")
                    return "Discover";
                else if (cCNum.charAt(0)=="37")
                      return "American Express";
                else
                    return "Unknown card type;" // You forgot this.
  } // and this
  

  Eddie : There are way more errors than just this. For example: cCNum.charAt(0)=="4"

  Paulo Guedes : @Eddie good point, Eddie. Didn't notice. :-)

• There are many syntax errors in the code you have provided us, so it's difficult to really find your root problem:

  • long.parselong(cCNum); instead of Long.parseLong(cCNum);
  • JOptionPane.showMessageDialog takes two arguments, not just one.
  • cCNum.charAt(0) == "4" doesn't work because you're comparing a char to a 1 byte string
  • cCNum.charAt(0) == "37" doesn't work because you're comparing a char to a two-byte string
  • You have a do { ... } that is missing while ....;
  • Parenthesis not balanced: while (cCNum.length() < 13) || (cCNum.length() > 16) && (num < 3) && validInt (cCNum) ) should be while ( (cCNum.length() < 13) || (cCNum.length() > 16) && (num < 3) && validInt (cCNum) )
  • JOptionPane.showMessageDialog(null,"Your card is a" + cCType ); uses an undefined variable cCType
  • You didn't close the method before public static String cCType (String cCNum)
  • public static String cCType (String cCNum) does not have its opening and closing curly braces
  • return "Unknown card type;" should be return "Unknown card type";
  • cCNum.charAt(0)=="4" should be either cCNum.charAt(0)=='4' or cCNum.startsWith("4") (and so on for the next few cases)
  • cCNum.charAt(0)=="37" should be cCNum.startsWith("37")
  • In public static boolean validInt(String num) you then define int num; where you probably want long number;
  • public static boolean validInt(String num ) is missing two closing curly braces -- one for the try/catch and one for the method close brace.
  • There are two too many closing braces before sumOfEvenPlaces, causing it to be declared outside the class.
  • In sumOfEvenPlaces() you use number without declaring it.
  • In sumOfEvenPlaces() you are missing the semi-colon on the return statement as well as on total+=add
  • In sumOfEvenPlaces() you use getDigit although your method is getDigits.
  • In sumOfOddPlace() you use number and sum without defining or initializing them.
  • You define sumOfOddPlace() but use sumOfOddPlaces().
  • in isValid your parenthesis don't balance.
  • There are general problems with int and longs being interchanged where they shouldn't be.

  I recommend that you use an IDE for Java (or C# or any other sufficiently advanced language) development. It will help a LOT with these sorts of errors, making them jump out and be more obvious. For Java, there are two free high quality IDEs: NetBeans (from Sun) and Eclipse.

  Bombe : +1 for total pwnage. :)

  Ray Hidayat : Wow that's amazing!

  Andy White : Yowsa, that earns a +1

• Don't roll your own code.

  Use an existing one from Apache Commons Validator

  http://commons.apache.org/validator/api-1.3.1/org/apache/commons/validator/CreditCardValidator.html

  Learning : Looking at the quality of the code , this is indeed an appropriate answer! +1